In many traffic situations it is desired to acquire an enhanced braking effect, for example at possible collision situations and when the road grip is lost. One way to achieve an enhanced braking effect is described in EP 2311695, where a braking mat is pressed against the road by at least one airbag in a chamber, where the chamber may evacuated in order to obtain a larger pressure from said airbag. This arrangement only relies on the effect of braking friction forces due to pressure from the braking mat against the road.
Another similar arrangement is described in U.S. Pat. No. 8,356,685, where a braking plate may be lowered. When lowered, a vacuum chamber of the plate faces the road, the vacuum chamber being evacuated such that a retaining function is obtained by the plate being pressed against the road due to the lowered pressure in the vacuum chamber. The lowered pressure is obtained by means of a gas generator acting on a so-called Venturi tube.
However, for such an arrangement, it is likely that the time between activation of the braking plate and the evacuation is too long for acquiring a braking effect in time. It is also likely that the pressure fall will be insufficient for obtaining a suitable braking effect whatsoever.